Variable drive with protection against jamming for movable parts

ABSTRACT

In a displacement drive that provides an obstruction prevention function for movable parts, in particular such as windows and sunroofs in motor vehicles, a decrease in the rotation speed or velocity of the drive is provided in order to achieve a predefined spring rate in specific displacement ranges so as to lower the kinetic energy. Within the predefined range before the closed position is reached, the rotation speed and/or the output of the drive is reduced linearly. The reduction to a minimum rotation speed or minimum output takes place within a specific position range. The minimum rotation speed or minimum output is reached at a specific position before the closed position and is substantially constant. Corresponding to different supply output levels, a linear reduction, for example, is performed along lines of different slopes, the length of the specific position range in which the reduction is performed being constant.

BACKGROUND INFORMATION

The present invention relates to a displacement drive with anobstruction prevention function for movable parts such as, for example,windows and sunroofs in motor vehicles.

In a displacement drive of this kind known from German Published PatentApplication No. 37 36 400 A1, a decrease in the rotation speed orvelocity of the drive is performed in order to achieve a predefinedspring rate in specific displacement ranges so as to lower the kineticenergy. The movable part is moved by way of a drive motor, through anobstruction hazard range in which foreign objects may become jammedbetween the movable part and a stationary part, into a closed position.Because of unavoidable delays in signal processing and the inertia ofthe mechanically moved part, the foreign object can be jammed betweenthe moved part and the stationary part despite a safety apparatusrepresenting the obstruction prevention function. To prevent this,provision is made in the case of this known displacement drive for thedisplacement velocity during closing of the movable part to bediminished in the obstruction hazard range. The actual obstructionprevention function can then, if applicable, halt the movable partmomentarily and possibly reverse the direction of motion.

With this known displacement drive, the decrease in velocity takes placein stages, i.e. operation is switched in one step from a high stage to alow stage of the closing velocity. Switching down abruptly in thisfashion can cause the obstruction prevention function to respondincorrectly, and moreover lengthens the closing time.

SUMMARY OF THE INVENTION

According to the present invention, a displacement drive with anobstruction prevention function provides a continuous transition from ahigh closing velocity to a specific low closing velocity, with anoptimized closing time. An incorrect response of the obstructionprevention function is thus reliably prevented.

According to the present invention, this is achieved in principle inthat within the predefined range before the “closed” position isreached, the rotation speed and/or the output of the drive is reduced inaccordance with a predefined functional relationship. The reduction to aminimum rotation speed or minimum output takes place within a specificposition range. This minimum rotation speed or minimum output is reachedat a specific position before the “closed” position. The minimumrotation speed or minimum output is substantially constant. Thereduction in the rotation speed and/or output of the drive can bepredefined in accordance with an arbitrarily selectable functionalrelationship. Smooth transitions can thereby be implemented.

In an advantageous embodiment of the displacement drive according to thepresent invention, the reduction in rotation speed is linear. The effortfor determining the support points is low.

A further embodiment according to the present invention is based on areduction in accordance with an exponential function. This allows abruptchanges in rotation speed and/or output to be avoided.

According to a particularly advantageous embodiment of the presentinvention, the reduction to the minimum rotation speed or minimum outputin accordance with a predefined functional relationship is accomplishedover a constant position range, the rate of reduction changing as afunction of the instantaneous supply power level, in particular thesupply voltage.

According to a particularly advantageous further alternative embodimentof the present invention, the reduction to the minimum rotation speed orminimum output is accomplished over a variable position range, thestarting point thereof changing as a function of the respectiveinstantaneous supply power level, in particular the supply voltage.

In a particularly advantageous embodiment of the present invention, thenecessary minimum rotation speed or minimum output is ascertainedempirically, such that sufficiently high closing forces are stillguaranteed under all conditions, in particular of temperature andhumidity.

In an advantageous embodiment of the present invention, control of therotation speed or output of the preferably electrical drive isaccomplished using semiconductor components, in particular linearcontrollers or clock-pulse controllers having a variablepulse-to-interpulse ratio.

In a particularly advantageous embodiment of the present invention,provision is made for the displacement drive to be usable together witha circuit for preventing foreign objects from being jammed between themoved part and fixed stop in the “closed” position.

According to an advantageous embodiment of this development of thepresent invention, the respective known slope of the reduction inaccordance with a predefined functional relationship in the rotationspeed and/or output of the drive can be taken into account as acorrection factor in calculating the reduction in rotation speed due toobstruction events.

In a particularly advantageous embodiment of the present invention,there is provided for the correction an adaptive memory in which thecontrolled reduction in rotation speed and/or output is stored as aslight slowing.

According to a further advantageous embodiment of the displacement driveaccording to the present invention, in order to improve the analysis forthe obstruction prevention function, the resolution for position sensingis increased by using an EXOR member between two Hall sensors, and/or byusing a multiply polarized ring magnet.

A further advantageous embodiment of the present invention provides thatwhen a very small opening width, for example<4 mm, is reached, therotation speed and/or output can be raised back up to the greatestpossible value in order to achieve maximum closing force, in particularin the area of rubber seals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a diagram of a first embodiment of thedisplacement drive according to the present invention, in which anobstruction prevention function is provided and in which a linearvelocity reduction takes place over a constant position range withdifferent changes in velocity.

FIG. 2 schematically shows a diagram of a second embodiment of thedisplacement drive according to the present invention, in which anobstruction prevention function is provided and in which a linearvelocity reduction takes place over a variable position range with aconstant change in velocity.

DETAILED DESCRIPTION

The displacement drive according to the present invention ischaracterized by a reduction in rotation speed and/or output inaccordance with a predefined functional relationship.

The predefined functional relationship for reduction in rotation speedand/or output encompasses the entire spectrum of continuous or discretemathematical functions suitable for achieving the reduction. In additionto the linear profile described with reference to the exemplaryembodiment, a reduction in accordance with an exponential function ispossible. With this it is possible to implement acceleration ordeceleration operations which guarantee a smooth transition between thetwo rotation speed and/or output stages. This can also be achieved byway of a reduction in accordance with a sine, cosine, or tangentfunction, and their inverse functions. Nth-degree polynomials alsoprevent an abrupt transition, thus decreasing the risk of jamming thepulley. As a representative of the functional relationships describedhere, the exemplary embodiment of the present invention refers to alinear reduction. The explanations relating thereto may be transferredto any function.

In FIG. 1, the velocity profile of a first embodiment of thedisplacement drive according to the present invention with obstructionprevention function is depicted schematically in a diagram. With thisembodiment, a linear velocity reduction takes place over a constantposition range 10 with different changes in the velocity of the movedpart or the rotation speed n of the motor being used, which preferablyis an electric motor. The output P or rotation speed n of thedisplacement drive is plotted on the vertical axis. Plotted on thehorizontal axis is the distance x traveled by the driven movable part,up to the immovable stop in the “closed” position depicted by the thickvertical line 11, in the region of an obstruction hazard that is ofinterest in the context of the present invention, namely up to positionx0.

According to the embodiment of FIG. 1, the output P or rotation speed nis reduced linearly in a specific position range, namely between x4 andx3, prior to reaching the “closed” position x0, to a minimum valuep_(min) or n_(min). A kind of terminal deceleration thus occurs towardposition x3, at which the minimum value is intended to be reached. Thisminimum value is then held constant until the “closed” position isreached. It is of sufficient magnitude to allow reliable travel all theway to x0. This minimum value is ascertained empirically, advantageouslyin consideration of the respective circumstances, for each system inwhich the invention is used. This minimum value is selected to be ofsufficient magnitude that reliable travel all the way to the “closed”position x0 is possible in all circumstances, i.e. for example alsotaking into account different temperatures and humidity levels.

With the embodiment depicted in FIG. 1, the specific position range 10within which the reduction takes place has a constant length x4−x3, andthe reduction in output P and/or rotation speed n takes place with adifferent slope corresponding to lines 12, 13, and 14. The linearreduction is terminated when a specific position, i.e. x3, is reached.At that point, a minimum value for output P_(min) and/or rotation speedn_(min) has been reached. With lines 12 the slope is greatest, so thatthe reduction rate of the decline in output or rotation speed is alsogreatest. This line 12 begins at position x4 from maximum outputP_(max), which may correspond, for example in the case of a motorvehicle, to the maximum supply voltage of the battery. With lines 13,the slope is less than with lines 12, so that the reduction rate of thedecline in output or rotation speed is also less. This line 13 begins atposition x4 from a lower output P2, which may correspond, for example inthe case of a motor vehicle, to a battery supply voltage which is lessthan the maximum. With lines 14 the slope is even less, and thereduction rate of the decline in output or rotation speed is thus alsoeven less. This line 14 also begins at position x4, but from an outputP1 which corresponds, for example in the case of a motor vehicle, to aneven lower battery supply voltage. The minimum output P_(min) may beassociated with the minimum permissible supply voltage. The linearreduction is thus accomplished in such a way that regardless of theinstantaneous supply power level, the procedure always begins at aspecific position, i.e. x4. At a fixed position, i.e. x3, the reductionterminates at the minimum value. With this embodiment the differences ininstantaneous supply output are taken into account by the differingslopes of lines 12, 13, 14, or in other words by way of a variable rateof change for the reduction.

In the case of the embodiment of the present invention for which adiagram is depicted schematically in FIG. 2, in the specific positionrange 10, i.e. between positions x4 and x3, the linear reduction to theminimum rotation speed n_(min) or minimum output P_(min) is accomplishedover variable reduction distances, the starting points thereof changingas a function of the instantaneous supply output level, in particularthe supply voltage. The slope of lines 24 is constant, corresponding toa constant rate of change for the reduction. The starting point for thebeginning of the respective reduction varies in accordance with thevarious supply output levels, in particular the supply voltage of amotor vehicle battery. Since the reduction is complete in each case atposition x3, the reduction distance labeled 20 at maximum supply outputP_(max) is the longest. The associated reduction distance 21 is shorterto correspond with the lower output P2. The reduction distance labeled22 is even shorter, in accordance with the supply output PI which iseven lower as compared with P2. With this embodiment, the differences ininstantaneous supply output level are taken into account by way of thevariable length of reduction distances 20, 21, 22, at a constant rate ofchange for the reduction.

The displacement drive configured according to the present invention isadvantageously used together with a circuit for preventing jamming offoreign objects between the moved part and fixed stop, labeled 11 in theFigures, in the “closed” position x0. The reduction rates resulting fromthe reduction according to the present invention are small compared withthose which are evoked in the obstruction events. As a result, theactual obstruction prevention function, in which the closing movement isimmediately halted and the rotation direction is optionally reversed, isleft substantially uninfluenced. Since the linear slope of the reductionis known in each case, this can be taken into account by way ofcorresponding correction values when calculating the rotation speedreduction resulting from obstruction events. In particular, a suitableadaptive memory in which “self-taught” slowings of the system are storedcan be provided for the correction. In this case, the linear controlledreduction in output and/or rotation speed according to the presentinvention is saved and stored as a slight slowing. In calculating therotation speed reduction due to obstruction (the obstruction preventionfunction), on the other hand, the linear rotation speed reduction iscalculated out.

With the displacement drive according to the present invention,according to an advantageous embodiment control of the rotation speed oroutput is accomplished by way of semiconductor components, in particularin the form of a linear controller or a clock-pulse controller having avariable pulse-to-interpulse ratio. In this context, an electrical drivemotor is preferably used as the drive motor.

In a further embodiment of the present invention, an additionalimprovement in obstruction prevention function analysis can be achievedin that an increased resolution is used for position sensing. This canhappen with the use of an EXOR member between two Hall sensors whichoutput 90-degree phase-shifted position signals of the motor shaft, thusallowing a doubling in position accuracy to be attained. It can also beaccomplished, however, together with or by the alternative use of amultiply polarized ring magnet.

The displacement drive according to the present invention is used inparticular for opening and closing windows and sunroofs of motorvehicles. In this context, the position values indicated in FIGS. 1 and2 may be approximately 500 mm for x4, approximately 50 mm for x3,approximately 25 mm for x2, and approximately 4 mm for x1, in each casebefore the “closed” position x0. Position x2 at about 25 mm means, formany applications, the value at which the kinetic energy must in allcases be reduced to a value which is still sufficient for theobstruction forces to fall below a specific value, for example to beless than 100 N, the forces being measured on elastic rods whose springrate is 65 N/mm. The value for x3 is selected as approximately 50 mm forthis reason, so that the reduction in rotation speed and/or output tothe minimum value is achieved in all cases, even under the mostunfavorable conditions, at this predefined limit value. For an openingwidth of less than approximately 4 mm, i.e. between position x1 and x0,in the “rubber seal” range, the output P or rotation speed n can beraised back to the full output in order to obtain maximum closingforces. This is indicated in the two Figures by reference characters 15,16, 17, which are associated accordingly with the respectiveinstantaneous outputs P_(max), P2, and P1.

As a result of the reduction according to the present invention, inaccordance with a predefined functional relationship, in the velocity ofthe displacement drive to a minimum output and/or rotation speed value,the rate of change is known and predictable. This reduction isaccomplished either over a constant range with a variable slopecorresponding to the supply output level, or with a variable length orduration corresponding to the supply output level. In either case, thereduction to a minimum value takes place in an optimized manner to atarget point. The change in rotation speed evoked by the reduction inoutput and/or rotation speed performed according to the presentinvention is small compared to that evoked by obstruction events. Whencombined with a obstruction prevention circuit, the precondition istherefore created that because of the known rate of change, theobstruction prevention function is optimally and independentlyeffective, substantially unaffected thereby.

What is claimed is:
 1. A displacement drive having an obstructionprevention function for a movable part, comprising: a first arrangementfor stopping one of a rotation speed of the displacement drive and avelocity of the displacement drive in response to an obstruction in thepath of the movable part; and a second arrangement for reducingaccording to a predefined functional relationship, before a closedposition of the movable part is reached and within the specificdisplacement range, one of the rotation speed and an output of thedisplacement drive to a corresponding one of a minimum rotation speedand a minimum output, wherein: the reduction to one of the minimumrotation speed and the minimum output is performed within a specificposition range, one of the minimum rotation speed and the minimum outputis achieved at a specific position before the closed position of themovable part, and one of the minimum rotation speed and the minimumoutput is substantially constant for a finite period of time prior tothe movable part reaching the closed position.
 2. The displacement driveaccording to claim 1, wherein the movable part includes one of a windowof a motor vehicle and a sunroof of the motor vehicle.
 3. Thedisplacement drive according to claim 1, wherein the second arrangementreduces the one of the rotation speed and the output in accordance withthe predefined functional relationship to the corresponding one of theminimum rotation speed and the minimum output over a constant positionrange, and wherein a rate of reduction performed by the secondarrangement changes as a function of an instantaneous power supply levelprovided by a supply voltage.
 4. The displacement drive as defined inclaim 1, wherein the second arrangement reduces the one of the rotationspeed and the output in accordance with the predefined functionalrelationship to the corresponding one of the minimum rotation speed andthe minimum output over a variable position range, and wherein astarting point of the reduction performed by the second arrangementchanges as a function of an instantaneous power supply level provided bya supply voltage.
 5. The displacement drive according to claim 1,wherein the reduction provided by the second arrangement is performed ona linear basis.
 6. The displacement drive according to claim 1, whereinthe reduction provided by the second arrangement is performed inaccordance with an exponential function.
 7. The displacement driveaccording to claim 1, wherein the second arrangement determines one ofthe minimum rotation speed and the minimum output empirically in orderto provide a sufficiently high closing force for the movable part underan influence of a condition.
 8. The displacement drive according toclaim 7, wherein the condition includes one of a temperature conditionand a humidity condition.
 9. The displacement drive according to claim1, wherein the second arrangement includes a plurality of semiconductorcomponents.
 10. The displacement drive according to claim 9, whereineach of the plurality of semiconductor components includes one of alinear controller and a clock-pulse controller having a variablepulse-to-interpulse ratio.
 11. The displacement drive according to claim1, wherein the displacement drive is an electric drive.
 12. Thedisplacement drive according to claim 1, further comprising a connectionto a circuit for preventing the movable part from pinching a foreignobject against a fixed stop.
 13. The displacement drive according toclaim 1, wherein the second arrangement calculates the reduction in therotation speed due to an obstruction event as a function of a correctionfactor including a slope of the reduction of one of the rotation speedand the output in accordance with the predefined functionalrelationship.
 14. The displacement drive according to claim 13, furthercomprising an adaptive memory for storing the reduction in at least oneof the rotation speed and the output as a slight slowing.
 15. Thedisplacement drive according to claim 1, wherein the second arrangementincreases one of the rotation speed and the output to a maximum value inorder to provide a maximum closing force for the movable part when themovable part is within a predetermined opening width from the closedposition.
 16. The displacement drive according to claim 15, wherein thepredetermined opening width is less than approximately 4 mm.
 17. Thedisplacement drive according to claim 15, wherein the predeterminedopening width is in an area of a rubber seal.
 18. The displacement driveaccording to claim 1, wherein one of the minimum rotation speed and theminimum output is substantially constant for a finite period of timeprior to, and up to, the movable part reaching the closed position. 19.A displacement drive having an obstruction prevention function for amovable part, comprising: a first arrangement for stopping one of arotation speed of the displacement drive and a velocity of thedisplacement drive in response to an obstruction in the path of themovable part; and a second arrangement for reducing according to apredefined functional relationship, before a closed position of themovable part is reached and within the specific displacement range, oneof the rotation speed and an output of the displacement drive to acorresponding one of a minimum rotation speed and a minimum output;wherein the reduction to one of the minimum rotation speed and theminimum output is performed within a specific position range, one of theminimum rotation speed and the minimum output is achieved at a specificposition before the closed position of the movable part, and one of theminimum rotation speed and the minimum output is substantially constantfor a finite period of time prior to the movable part reaching theclosed position, and wherein the second arrangement subsequentlyincreases one of the rotation speed and the output to a maximum value inorder to provide a maximum closing force for the movable part when themovable part is less than approximately 4 mm from the closed position inan area of a rubber seal.